The present invention relates to a continuous film laminating and delaminating system. More particularly, the present invention relates to a system in which a film, e.g. a molding film, a photosensitive material film, a pressure-sensitive adhesive film, etc. is continuously laminated on and delaminated from a surface of a substrate, e.g. a duplicate plate, a hologram original plate, etc.
Conventional techniques will be explained below by taking the case of a hologram duplicating method in particular.
Duplication of a hologram original plate has heretofore been performed by applying laser light to the hologram original plate placed in close contact with a photosensitive material so that diffracted light from the original plate and the incident light interfere with each other in the photosensitive material, thereby recording a hologram image of the original plate in the photosensitive material. In this process, in order to prevent the disorder of the image due to the back reflection component produced by reflection at the reverse surface of the photosensitive material, an index matching liquid that is substantially equal to the original plate in refractive index is interposed between the original plate and the photosensitive material, thereby enhancing the adhesion and thus preventing back reflection during the duplication of the hologram image.
Incidentally, the index matching liquid, which is interposed between the hologram original plate and the photosensitive material, is a thick liquid and difficult to apply with a uniform thickness because of fluidity, thickness unevenness, vibration, etc. In particular, when a large amount of index matching liquid is applied, it is impossible to effect favorable duplication of a hologram due to the flow of the index matching liquid. Even if duplication of a hologram is carried out in a clean room, dust particles of 10 .mu.m or less in diameter may get mixed in the contact layer structure. If duplication is carried out with dust particles mixed in the contact layer structure, the dust particles undesirably lift the film of photosensitive material and cause duplicating defects due to the flow of the index matching liquid around the dust particles.
To solve such problems, Japanese Patent Application No. 4-327918 proposes a duplicating method and apparatus wherein a cushioning layer is used to bury dust particles to thereby reduce the incidence of duplicating defects. However, the proposed duplicating method and apparatus still suffer from problems in terms of durability and so forth.
In view of the above-described problems of the conventional technique, Japanese Patent Application No. 5-212954 discloses a system in which a film, e.g. a photosensitive material film, is continuously and surely brought into contact with a surface of a substrate, e.g. a hologram original plate, and it is continuously delaminated from the substrate surface.
The invention in the above-mentioned application will be explained below by way of an example in which it is applied to duplication of a hologram. It will, however, be clear from the following explanation that the use application of the system according to the invention is not necessarily limited to duplication of a hologram, but the system may also be applied to duplication of a relief pattern, preparation of a sample of a microscopic specimen, etc.
Duplication of a hologram is carried out as shown in FIG. 1(a). That is, a photosensitive material film 1 is brought into close contact with a surface of a hologram original plate 5 through an index matching liquid 6 having a refractive index substantially equal to that of the original plate 5. Then, laser light 7 is applied from the photosensitive material film side (or from the hologram original plate side, as described later) so that the light 7 and diffracted light 8 from the original plate 5 interfere with each other in the photosensitive material film 1, thereby recording a hologram image in the photosensitive material film 1. The photosensitive material film 1 for hologram recording, which is made of a photopolymer or the like, is usually composed of 3 layers, that is, a base film 3, a photosensitive material 2, and a base film 4. If minute dust particles 9 are mixed in the contact layer structure when the photosensitive material film 1 is brought into close contact with the hologram original plate 5, the dust particles 9 undesirably lift the film 1 and cause duplicating defects due to the flow of the index matching liquid 6 around the dust particles 9.
Therefore, the base film 3 that is closer to the original plate 5 is peeled off to expose the photosensitive material layer 2, which is a viscoelastic material, and the photosensitive material layer 2 is laminated directly on the original plate 5, as shown in FIG. 1(b), thereby burying the dust particles 9 in the layer 2, and thus making it possible to reduce the incidence of duplicating defects.
In this process, it is preferable to remove dust particles from the base films 3 and 4 by using gum rollers, as a matter of course. It is also preferable to use a static eliminator (ionized air spray, corona discharge, etc.) in order to suppress adsorption of dust particles due to static electricity generated when the base film 3 is peeled off.
In Japanese Patent Application No. 5-212954, however, the duplication is carried out by intermittently feeding the film 1 onto the original plate 5 in theory because the original plate 5 is in planar form.